a$.$ Suppose you are working with a chemical reactor that is used to handle an endo$-$thermic reaction that is heated by steam. To control the heat input you are allowed to use a pneumatic valve as a final control element. What is the valve type you will use? Explain.

b$.$ What are the pressure limits of commercial valves?

c$.$ Given the block diagram shown below,

What control scheme does the block diagram represent?

Determine the transfer function $G=\frac{Y}{x}.$